Why is the pointerover event used here instead of pointerdown?
pointercancel is dispatched in relation to a pointerdown event. While the pointerover event works here because the test is targeted at the touch pointer type (where the pointerover event is always triggered as a side effect of the pointerdown event), it's more logical to use the pointerdown event as the trigger point here. It would also allow us to re-use the same code for testing other pointer types.